Semiconductor devices having metal layers as barrier layers on upper or lower electrodes of capacitors

ABSTRACT

Semiconductor films include insulating films including contact holes in semiconductor substrates, capacitors comprising lower electrodes formed on conductive material films in the contact holes, high dielectric films formed on the lower electrodes and upper electrodes formed on the high dielectric films, and barrier metal layers positioned between conductive materials in the contact holes and the lower electrodes, the barrier metal layers including metal layers formed in A-B-N structures in which a plurality of atomic layers are stacked by alternatively depositing reactive metal (A), an amorphous combination element (B) for preventing crystallization of the reactive metal (A) and nitrogen (N). The composition ratios of the barrier metal layers are determined by the number of depositions of the atomic layers.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional application of Ser. No.09/511,598, filed Feb. 23, 2000, now U.S. Pat. No. 6,287,965, thedisclosure of which is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of forming a metal layer usingatomic layer deposition and a semiconductor device having the metallayer as a barrier metal layer or the upper or lower electrode of acapacitor.

2. Description of the Related Art

As the integration density of semiconductor devices increases, highdielectric materials having a large dielectric constant have beendeveloped to obtain large capacitance in a small area. For example, aBST (BaSrTiO₃) film having a perovskite crystal structure has adielectric constant of about several hundreds through one thousand in abulk state, which is different to a silicon nitride film, a siliconoxy-nitride film and a tantalum oxide (Ta₂O₅) film which areconventionally used for a capacitor. A BST film is advantageous in thata thin dielectric film can be implemented such that an equivalent oxidethickness is less than 10 Å even when the thickness of the BST film ismore than 500 Å. An electrode such as platinum (Pt) which is notoxidized may be used for a BST electrode. An electrode such as ruthenium(Ru) or iridium (Ir), which holds the characteristics of a conductoreven if it is oxidized and forms oxide ruthenium (RuO₂) or oxide iridium(IrO₂), may also be used for a BST electrode.

To obtain a high dielectric BST film having excellent capacitance andleakage current characteristics, a thermal process needs to be performedat a high temperature after depositing BST film. At this time, a barriermetal layer needs to be formed to prevent oxidation of an ohmic layerand a polysilicon plug due to diffusion of oxygen. The barrier metallayer is interposed between the polysilicon plug and a lower electrode.

Conventionally, a titanium nitride (TiN) film is usually used for thebarrier metal layer, but the TiN film is oxidized at a temperature ofmore than 450° C. When a high temperature thermal process is performedin an oxygen atmosphere after depositing a BST film, a TiN film and apolysilicon plug are oxidized because platinum (Pt) lets oxygen easilypass through. Especially, a non-conductive TiO₂ film is formed when theTiN film is oxidized. In addition, platinum (Pt) and silicon (Si) isdiffused into the TiN film, and thus the TiN film cannot act as abarrier metal layer. It is known that the diffusion of Pt and Si iscaused by the columnar structure of TiN. Accordingly, it is necessary torestrain the diffusion of oxygen by implementing an amorphous structurewhich dose not have a grain boundary acting as a path of diffusion.

From this necessity, compounds containing a refractory metal have beenstudied. A barrier metal layer formed of a compound containing arefractory metal has a problem that adjustability and reproducibility ofcomposition is decreased when the compound is deposited by chemicalvapor deposition, due to the complexity of the composition. Accordingly,a reactive sputtering process is usually performed in a nitrogenatmosphere when forming a barrier metal layer of a compound containing arefractory metal. However, a barrier metal layer formed by a sputteringprocess has a poor step coverage so that it cannot be suitable for abarrier metal layer in a capacitor, the structure of which becomes morecomplex as the integration density of a semiconductor device increases,for example, a barrier metal layer which is formed at the lower portionof a trench having a high aspect ratio in a trench type capacitor.

SUMMARY OF THE INVENTION

To solve the above problems, it is the first object of the presentinvention to provide a method of forming a metal layer using atomiclayer deposition, which has an excellent step coverage and preventsdiffusion of oxygen, by which method the composition of the metal layercan be appropriately adjusted so as to easily provide a desirableresistance and conductivity.

It is the second object of the present invention to provide asemiconductor device having the metal layer formed by the above methodas a barrier metal layer or the upper or lower electrode of a capacitor.

Accordingly, to achieve the first object, the present invention by afirst aspect provides a method of forming a metal layer having an A-B-Nstructure in which a plurality of atomic layers are stacked byindividually injecting pulsed source gases for a reactive metal (A), anamorphous combination element (B) for preventing crystallization of thereactive metal (A) and nitrogen (N), and nitrogen (N) and allowing thesource gases to be chemically adsorbed to a semiconductor substrate.

In particular, the source gases are alternately injected in apredetermined order to alternately arrange the atomic layers, and thenumber of injection pulses of each source gas is adjusted to determinethe composition of the metal layer.

The reactive metal (A) may be titanium (Ti), tantalum (Ta), tungsten(W), zirconium (Zr), hafnium (Hf), molybdenum (Mo) or niobium (Nb). Theamorphous combination element (B) for preventing crystallization of thereactive metal (A) and the nitrogen (N) may be aluminum (Al), silicon(Si) or boron (B). In addition, the electrical conductivity andresistance of the metal layer may be determined by adjusting the numberof injection pulses of a source gas for the amorphous combinationelement. The content of Al with respect to Ti may be 10-35% in a TiAlNlayer when the metal layer is the TiAlN layer.

Further, according to a second aspect of the present invention, aplurality of oxygen diffusion preventing layers, e.g., aluminum oxidelayers, may be formed in alternation with a plurality of metal layers soas to form a multiple metal layer including a plurality of metal layersand a plurality of oxygen diffusion preventing layers. Here, the oxygendiffusion preventing layer may be formed by alternately applying pulsedinjections of source gases for a metal element and oxygen to thesemiconductor substrate including the metal layer. The oxygen diffusionpreventing layer may be formed by performing the steps of forming amaterial layer containing oxygen on the metal layer using atomic layerdeposition and thermal-processing the semiconductor substrate includingthe metal layer and the material layer.

To achieve the second object, the present invention also provides asemiconductor device including an insulating film including a contacthole in a semiconductor substrate, a conductive material film formed onthe bottom of the contact hole, and a capacitor including a lowerelectrode formed on the conductive material film in the contact hole, ahigh dielectric film formed on the lower electrode and an upperelectrode formed on the high dielectric film.

In particular, the semiconductor device has a barrier metal layerbetween the conductive material film in the contact hole and the lowerelectrode. The barrier metal layer may be a metal layer formed in anA-B-N structure in which a plurality of atomic layers are stacked byalternately depositing a reactive metal (A), an amorphous combinationelement (B) for preventing crystallization of the reactive metal (A) andnitrogen (N), and nitrogen (N). The composition ratio of the barriermetal layer may be determined by the number of depositions of eachatomic layer.

The reactive metal (A) may be titanium (Ti), tantalum (Ta), tungsten(W), zirconium (Zr), hafnium (Hf), molybdenum (Mo) or niobium (Nb). Theamorphous combination element (B) for preventing crystallization of thereactive metal (A) and the nitrogen (N) may be aluminum (Al), silicon(Si) or boron (B). In addition, the electrical conductivity andresistance of the barrier metal layer may be determined by the number ofinjection pulses of an atomic layer of the amorphous combination element(B) to the total number of injection pulses used for the barrier metallayer.

The semiconductor device of present invention may also include an oxygendiffusion preventing layer, e.g., an aluminum oxide layer, on the metallayer. Accordingly, the barrier metal layer may be formed of a multiplemetal layer including a plurality of metal layers and a plurality ofoxygen diffusion preventing layers. In addition, a material layercontaining oxygen may be formed on the oxygen diffusion preventinglayer.

Further, to achieve the second object, the present invention provides asemiconductor device including a semiconductor device having a capacitorincluding a lower electrode formed on a predetermined material film on asemiconductor substrate, a high dielectric film formed on the lowerelectrode and an upper electrode formed on the high dielectric film.

In particular, the lower electrode may be formed in an A-B-N structurein which a plurality of atomic layers are stacked by alternately andsequentially depositing atomic layers of a reactive metal (A), anamorphous combination element (B) for preventing crystallization of thereactive metal (A) and nitrogen (N), and nitrogen (N). The compositionof the lower electrode can be determined by the number of depositions ofeach atomic layer. The upper electrode may be formed in the same manneras the lower electrode.

The reactive metal (A) may be titanium (Ti), tantalum (Ta), tungsten(W), zirconium (Zr), hafnium (Hf), molybdenum (Mo) or niobium (Nb). Theamorphous combination element (B) for preventing crystallization of thereactive metal (A) and the nitrogen (N) may be aluminum (Al), silicon(Si) or boron (B). In addition, the electrical conductivity andresistance of the lower electrode may be determined by the number ofinjection pulses of an atomic layer of the amorphous combination element(B) to the total number of injection pulses used for the lowerelectrode.

As described above, a metal layer (a multiple metal layer) formed byatomic layer deposition of the present invention has a high thermalresistant and high oxidation resistant characteristics. Since the metallayer is formed by individually depositing atomic layers, the stepcoverage thereof is excellent even in a very compact region. Inaddition, since individual atomic layers are adsorbed and formed in apredetermined order, the composition ratio of each element contained inthe metal layer can be easily adjusted. A metal layer formed by atomiclayer deposition of the present invention may be employed as a barriermetal layer, a lower electrode or an upper electrode in a semiconductordevice.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objective and advantages of the present invention will becomemore apparent by describing in detail preferred embodiments thereof withreference to the attached drawings in which:

FIGS. 1A and 1B are graphs for showing an example of a method ofinjecting source and purge gases for deposition of an atomic layer whena metal layer is formed according to a first aspect of the presentinvention;

FIGS. 2A and 2B are graphs for showing another example of a method ofinjecting source and purge gases for deposition of an atomic layer whena metal layer is formed according to a first aspect of the presentinvention;

FIG. 3 is a graph for showing changes in the specific resistance of atitanium aluminum nitride (TiAlN) layer as the composition ratio of Alincreases;

FIG. 4 is a graph for showing an XRD result of a TiAlN layer formedaccording to the present invention;

FIG. 5 is SEM photographs showing the surfaces of a conventionaltitanium nitride (TiN) film and a TiAlN layer according to the presentinvention;

FIG. 6 is a graph showing changes in surface resistance (Rs) of a TiAlNlayer which is thermal-processed in an oxygen atmosphere to test thethermal resistant and the oxidation resistant characteristics of a TiAlNlayer of the present invention;

FIGS. 7A through 7D are sectional views for explaining a method offabricating a semiconductor device employing a metal layer as a barriermetal layer according to an embodiment of the present invention;

FIGS. 8A through 8E are sectional views for explaining a method offabricating a semiconductor device employing a metal layer as the upperelectrode of a capacitor according to the embodiment of the presentinvention;

FIGS. 9A through 9E are sectional views for explaining a method offabricating a semiconductor device employing a metal layer as the lowerelectrode of a capacitor according to an embodiment of the presentinvention;

FIG. 10 is a sectional view for explaining a method of forming a metallayer using atomic layer deposition according to a second aspect of thepresent invention;

FIG. 11 is a graph for showing an example of a method of injectingsource and purge gases for deposition of an atomic layer when formingthe oxygen diffusion preventing layer of FIG. 10;

FIGS. 12 and 13 are sectional views for explaining a method of forming ametal layer using atomic layer deposition according to a third aspect ofthe present invention; and

FIGS. 14 and 15 are sectional views for explaining a method offabricating a semiconductor device employing a metal layer, which isformed by atomic layer deposition according to the second and thirdaspects of the present invention, as a barrier metal layer.

DETAILED DESCRIPTION OF THE INVENTION

With reference to the accompanying drawings, the preferred embodimentsof the present invention will be described.

Method for Forming Metal Layer Using Atomic Layer Deposition Accordingto First Aspect of the Present Invention

Atomic layer deposition is a method of sequentially depositing aplurality of atomic layers on a semiconductor substrate by sequentiallyinjecting and removing reactants into and from a chamber. The atomiclayer deposition uses a chemical reaction like chemical vapor deposition(CVD), but it is different to CVD in that reactant gases areindividually injected in the form of a pulse instead of simultaneouslyinjecting reactant gases, so they are not mixed in the chamber. Forexample, in case of using gases A and B, gas A is first injected into achamber and the molecules of gas A are chemically adsorbed to thesurface of a substrate, thereby forming an atomic layer of A. The gas Aremaining in the chamber is purged using an inert gas such as an argongas or a nitrogen gas. Thereafter, the gas B is injected and chemicallyadsorbed, thereby forming an atomic layer of B on the atomic layer of A.Reaction between the atomic layer of A and the atomic layer of B occurson the surface of the atomic layer of A only. For this reason, asuperior step coverage can be obtained regardless of the morphology of asurface. After the reaction between the atomic layers of A and B, gas Bremaining in the chamber and byproducts of the reaction are purged. Thethickness of a film can be adjusted in atomic layer units by repeatinginjection of gas A or B and deposition of an atomic layer.

The following description concerns a method for forming a metal layerusing atomic layer deposition according to a first aspect of the presentinvention. The metal layer is formed in a structure in which a pluralityof atomic layers are stacked in an A-B-N structure, wherein A is areactive metal, B is an element for amorphous combination, and N isnitrogen. The reactive metal (A) is a transition metal such as titanium(Ti), tantalum (Ta), tungsten (W), zirconium (Zr), hafnium (Hf),molybdenum (Mo) or niobium (Nb). The amorphous combination element (B)is either aluminum (Al), silicon (Si) or boron (B). The amorphouscombination element (B) may also be the same as the element used for thereactive metal (A).

The amorphous combination element (B) prevents combination of thereactive metal (A) and nitrogen (N), thereby forming a metal layerhaving an amorphous structure. The amorphous combination element (B)also prevents a metal layer having an A-B-N structure from beingcrystalized in a succeeding thermal process.

A representative metal layer of the present invention is a titaniumaluminum nitride (TiAlN) film. One among titanium chloride (TiCl₄),tetrakis demethyl amino titanium (TDMAT) and tetrakis deethyl aminotitanium (TDEAT) is used as a source gas for Ti when forming a TiAlNlayer. One among trimethyl aluminum (TMA), triethyl aluminum (TEA),tri-I-buthyl aluminum (TIBA) and AlClx is used as a source gas for Al.One among N₂ and NH₃ is used as a source gas for N.

In forming a TiAlN layer, a semiconductor substrate is first loaded inan atomic layer deposition chamber. Subsequently, source gases for threeelements constituting a metal layer, i.e., a reactive metal (A),aluminum (Al) and nitrogen (N), are supplied from a gas supply unitthrough a gas supply pipe into the atomic layer deposition chamber. Thesource gases are individually and alternately supplied in the form of apulse, thereby stacking Ti, Al and N atomic layers on the semiconductorsubstrate. The composition ratios of Ti, Al and N in the metal layer canbe adjusted by appropriately determining the injection order of thesource gases, the number of injections of each gas, and the injectiontime of source gases. Particularly, the composition of the metal layercan be adjusted according to the number of depositions of an atomiclayer of an amorphous combination element, for example, Al, so that adesired electrical conductivity and resistance of the metal layer can beprovided. The following description concerns examples of adjustment ofcomposition of Ti, Al and N.

FIGS. 1A and 1B are graphs for showing an example of a method ofinjecting source and purge gases for deposition of an atomic layer whena metal layer is formed according to a first aspect of the presentinvention. Referring to FIGS. 1A and 1B, TiCl₄, TMA and NH₃ isrepeatedly injected in a cycle of TiCl₄-TMA-TiCl₄—NH₃, thereby forming aTiAlN layer containing an abundance of Ti. It is preferable that thetemperature of a substrate is 300-700° C., the inner pressure of achamber is 0.1-10 torr, and a pulse-on time for which a source gas isinjected is 0.1-10 seconds.

FIG. 1A shows a case in which purge operation is performed bycontinuously injecting a purge gas while the source gases are beinginjected. FIG. 1B shows a case in which purge operation is performed byinjecting a purge gas in the form of a pulse between the injectionpulses of the source gases. One among Ar, N₂ and He gases is used forthe purge gas.

FIGS. 2A and 2B are graphs for showing another example of a method ofinjecting source and a purge gas for deposition of an atomic layer whena metal layer is formed according to a first aspect of the presentinvention. Referring to FIGS. 2A and 2B, TiCl₄, TMA and NH₃ isrepeatedly injected in a cycle of TiCl₄—NH₃—TMA—NH₃, and a pulse-on timeof TMA is longer than that of TiCl₄, thereby forming a TiAlN layercontaining an abundance of Al. The conditions of a chamber is the sameas those in FIGS. 1A and 1B. In other words, the temperature of asubstrate is 300-700° C., the inner pressure of a chamber is 0.1-10torr, and a pulse-on time for which a source gas is injected is 0.1-10seconds.

FIG. 2A shows a case in which purge operation is performed bycontinuously injecting a purge gas while the source gases are beinginjected. FIG. 1B shows a case in which purge operation is performed byinjecting a purge gas between the injection pulses of the source gases.One among Ar, N₂ and He gases is used for the purge gas.

The deposition ratio of each atomic layer can be appropriately adjustedby appropriately adjusting the number of injections of each source gasusing the above methods. The electrical conductivity and resistance ofeach atomic layer vary depending on the deposition ratio of each atomiclayer as shown in Table 1.

TABLE 1 Sample 1 Sample 2 Sample 3 Ti  35%  24%  21% Al  15%  26%  31% N 30%  35%  35% C  17%  10%   8% Cl  3%   3%   3% Ti:AL 1:0.43 1:1.11:1.48 Specific resistance ρ 589 3701 9161 (μΩ-cm)

Referring to Table 1, it can be seen that the specific resistance of theTiAlN layer increases as the content of Al with respect to the contentof Ti increases in the composition of the TiAlN layer. Since a specificresistance ρ is proportional to the reciprocal of the electricalconductivity, the electrical conductivity decreases as the specificresistance increases. Accordingly, the TiAlN layer can be properlyformed to have an electrical conductivity and a resistance proper to theusage thereof.

FIG. 3 is a graph showing change in specific resistance of a TiAlN layeras the ratio of AlN to TiN+AlN increases in the composition of the TiAlNlayer. Referring to FIG. 3, it can be seen that the specific resistanceof the TiAlN layer increases as the content of Al increases in thecomposition of the TiAlN layer. When the TiAlN layer is used as a upperelectrode or a barrier metal layer between a polysilicon layer and thelower electrode of a capacitor, the specific resistance may varyaccording to the pattern of a device, but preferably is 300-10000 μΩ-cm.Accordingly, the content of Al with respect to the content of Ti ispreferably 10-35% in the TiAlN layer.

FIG. 4 is a graph for showing an XRD result of a TiAlN layer formedaccording to the present invention. FIG. 5 is SEM photographs showingsurfaces of a conventional titanium nitride (TiN) layer and a TiAlNlayer according to the present invention. More specifically, the uppergraph of FIG. 4 is the XRD result of a TiAlN layer containing anabundance of Ti, and the lower graph is the XRD result of a TiAlN layercontaining an abundance of Al. As shown in FIG. 4, it can be seen that aTiAlN layer formed according to the first aspect of the presentinvention is in an amorphous state as a whole even though slight TiAlNpeaks are observed. As shown in FIG. 5, a TiAlN layer of the presentinvention has a much more planar surface than a conventional TiN layer.

FIG. 6 is a graph showing changes in surface resistance (Rs) of a TiAlNlayer which is thermal-processed in an oxygen atmosphere to test thethermal resistant and the oxidation resistant characteristics of a TiAlNlayer of the present invention. In FIG. 6, a reference character “A”indicates a case in which no process is performed. “B” indicates a casein which a thermal process is performed at 0.1 torr and 600° C. in an O₂atmosphere for 30 minutes. “C” indicates a case in which a thermalprocess is performed at 0.1 torr and 700° C. in an O₂ atmosphere for 30minutes. Referring to FIG. 6, the Rs (“B”) of a TiAlN layer of 250 Å,which is thermal-processed at 0.1 torr and 600° C. in an oxygenatmosphere for 30 minutes, rarely changes compared to the Rs (“A”) of aTiAlN on which no process is performed. Accordingly, it can be seen thatthe TiAlN has an excellent thermal and oxidation resistantcharacteristics. The TiAlN of the present invention shows excellentthermal and oxidation resistant characteristics because Al in the TiAlNlayer transfers to the surface of the TiAlN layer during thermalprocessing thereby to form an oxide film, i.e., an Al₂O₃ film, on thesurface of the TiAlN layer, and thus diffusion of oxygen is prevented.

As described above, a TiAlN layer shows high thermal and oxidationresistant characteristics, and has an excellent step coverage even in avery compact region since atomic layers are individually deposited.Since individual atomic layers are sequentially adsorbed and formed, thecomposition of the TiAlN layer can be adjusted more easily and thereproducibility of the composition is excellent compared to CVD.

A trench type capacitor having a metal layer, which is formed by atomiclayer deposition as described above, as a barrier metal layer and amethod for fabricating the capacitor will be described in detail in afirst embodiment. A cylinder type capacitor having the metal layer as anupper electrode and a method for fabricating the capacitor will bedescribed in detail in a second embodiment. A trench type capacitorhaving the metal layer as a lower electrode and a method for fabricatingthe capacitor will be described in detail in a third embodiment.

First Embodiment

Referring to FIG. 7A, an insulating layer 210 composed of a siliconoxide (SiO₂) film is formed on a semiconductor substrate 104.Subsequently, the insulating layer 210 is photo-etched to form a contacthole.

Referring to FIG. 7B, the contact hole may be partially filled to apredetermined depth or not filled at all to give a desired capacitance.When partially filling the contact hole, the contact hole is filled withpolysilicon and then wet etching or wet etching combined with chemicalmechanical polishing is performed on the polysilicon to leave apolysilicon film 212 of a predetermined thickness at the bottom of thecontact hole.

Referring to FIG. 7C, a barrier metal layer 214, which is improved inthermal and oxidation resistant characteristics, is formed on theinsulating layer 210 and on the polysilicon film 212. The barrier metallayer 214 is a conductive layer in which the atomic layers of a reactivemetal (A), an amorphous combination element (B) for preventingcrystallization of the reactive metal and nitrogen (N), and nitrogen (N)are sequentially stacked by atomic layer deposition. For the reactivemetal (A), Ti, Ta, W, Zr, Hf, Mo or Nb is used, and for the amorphouscombination element (B), Al, Si or B is used. The amorphous combinationelement prevents the combination of the reactive metal and the nitrogen,thereby forming the barrier metal layer having an amorphous structure.

For example, for the barrier metal layer, pulsed injections of thesource gases TiCl₄, TMA and NH₃ of a reactive metal (Ti), an amorphouscombination element (Al) and nitrogen (N), respectively, are supplied,and the source gases are chemically adsorbed to the polysilicon film212, thereby forming a TiAlN layer composed of a plurality of atomiclayers. The TiAlN layer has a structure in which atomic layerscorresponding to the source gases are alternately stacked since thesource gases are alternately and individually supplied in apredetermined order. The TiAlN layer shows excellent thermal andoxidation resistant characteristics as described above. The ratios ofthe contents of Ti, Al and N constituting the barrier metal layer 214 tothe total content of the barrier metal layer 214 are determined by thetotal number of injection pulses of the corresponding source gases. Byappropriately determining the composition ratios, desirable electricalconductivity and resistance can be accurately obtained.

For the adjustment of composition, examples described above withreference to FIGS. 1A through 2B can be adopted, and the same conditionsas described in the examples can be adopted in the deposition of atomiclayers. Purge operation may be performed by continuously injecting apurge gas without interruption while the source gases are being injectedas shown in FIGS. 1A and 2A. Alternatively, purge operation may beperformed by injecting a purge gas between the injection pulses of thesource gases as shown in FIGS. 1B and 2B. The purge gas is Ar, N₂, orHe.

After forming the TiAlN layer on the polysilicon film 212 and theinsulating layer 210, the portion of the TiAlN layer deposited outsideof the contact hole is etched back and removed by wet etching orchemical mechanical polishing, thereby leaving only the portion of thebarrier metal layer 214 formed in the contact hole. The barrier metallayer 214 formed using atomic layer deposition according to the presentinvention can be made to be thick in contrast to a conventional one. Inaddition, the thickness of the barrier metal layer 214 can be easilyadjusted, and the composition of the barrier metal layer 214 can beeasily and accurately adjusted. The specific resistance of the barriermetal layer 214 is preferably 300-10000 μΩ-cm. Accordingly, thecomposition ratio of Al is adjusted such that the content of Al withrespect to Ti is about 10-35% in the TiAlN layer.

Referring to FIG. 7D, a trench type lower electrode 216 composed of ametal such as Cu, Al or W is formed on the resultant structure. Thebarrier metal layer 214 is particularly excellent in preventingdiffusion when the lower electrode 216 is a metal which is easilydiffused, such as Cu. Next, a tantalum oxide film (Ta₂O₅) or aferroelectric substance, such as PZT ((Pb, Zr)TiO₃), BST ((Ba, Sr)TiO₃)or STO (SrTiO₃), having a large dielectric constant is deposited on thetrench type lower electrode layer 216 to form a dielectric film 218.Then, an upper electrode 220 is formed on the dielectric film 218.

Second Embodiment

With reference to FIGS. 8A through 8E, a cylinder type capacitoremploying a metal layer formed by atomic layer deposition as an upperelectrode will be described. Referring to FIG. 8A, an insulating layer210 composed of a silicon oxide (SiO₂) film is formed on a semiconductorsubstrate 104. Subsequently, photo etching is performed to form acontact hole in the insulating layer 210.

Referring to FIG. 8B, the contact hole is filled with a conductivematerial to form a plug 212. For example, the contact hole may be filledwith doped polysilicon to form a poly plug.

Referring to FIG. 8C, a cylinder type lower electrode 214 composed of ametal such as Al or W is formed on the insulating layer 210 and the plug212 using a photoresist pattern (not shown). Next, a barrier metal layer216 is formed of TiN or TaN between the cylinder type lower electrode214 and the poly plug 212 to prevent oxidation of the poly plug 212during a later thermal process. When the lower electrode 214 is a metalwhich is easily diffused, such as Cu, the barrier metal layer 216 ispreferably composed of a metal layer of a ternary group, for example, aTiSiN layer, a TaSiN layer or a TiAlN layer, which is particularlyexcellent in preventing diffusion.

Referring to FIG. 8D, a tantalum oxide film (Ta₂O₅) having a largedielectric constant or a ferroelectric substance such as PZT ((Pb,Zr)TiO₃), BST ((Ba, Sr)TiO₃) or STO (SrTiO₃), is deposited to form adielectric film 218 surrounding the cylinder type lower electrode layer214.

Referring to FIG. 8E, an upper electrode 220 having an A-B-N structureaccording to the present invention is formed on the dielectric film 218.The upper electrode 220 is a conductive layer in which atomic layers ofa reactive metal (A), an amorphous combination element (B) forpreventing crystallization of the reactive metal and nitrogen (N), andnitrogen (N) are sequentially stacked by atomic layer deposition. Thecomposition ratio of an atomic layer of the upper electrode 220 isdetermined according to the number of injection pulses of the atomiclayer to the total number of injection pulses used for the upperelectrode 220, and the electrical conductivity and resistance of theupper electrode 220 can be appropriately determined by adjusting theratio of the number of atomic layers formed of the amorphous combinationelement (B) to the combined number of other atomic layers. The reactivemetal (A) may be Ti, Ta, W, Zr, Hf, Mo or Nb. The amorphous combinationelement (B) for preventing crystallization of the reactive metal (A) andthe nitrogen (N) may be Al, Si or B.

In this embodiment, the upper electrode 220 is formed of a TiAlN layer.When forming the TiAlN layer, one among titanium chloride (TiCl₄),tetrakis demethyl amino titanium (TDMAT) and tetrakis deethyl aminotitanium (TDEAT) is used as a source gas for Ti. One among trimethylaluminum (TMA), triethyl aluminum (TEA), tri-I-buthyl aluminum (TIBA)and AlClx is used as a source gas for Al. One among N₂ and NH₃ is usedas a source gas for N.

More specifically, in forming the upper electrode 220, pulsed injectionsof source gases for a nitrogen material of a ternary group aresequentially supplied into an atomic layer deposition chamber in apredetermined order thereby to sequentially stack atomic layers on thehigh dielectric film 218 on the semiconductor substrate 104.

To form a TiAlN layer as the upper electrode 220, pulsed injections ofsource gases TiCl₄, TMA and NH₃ of a reactive metal (Ti), an amorphouscombination element (Al) and nitrogen (N), respectively, are supplied,and the source gases are chemically adsorbed to the high dielectric film218, thereby forming a plurality of atomic layers. The upper electrode220 has a structure in which atomic layers corresponding to each of thesource gases are alternately stacked since the source gases areindividually supplied. The ratios of the contents of Ti, Al and Nconstituting the upper electrode 220 to the total content of the upperelectrode 220 are determined by appropriately adjusting the total numberof injections of the corresponding source gases. By appropriatelydetermining the composition ratios, desirable electrical conductivityand resistance can be accurately obtained.

For the adjustment of composition, examples described above withreference to FIGS. 1A through 2B can be adopted, and the same conditionsas described in the examples can be adopted in the deposition of atomiclayers. Purge operation may be performed by continuously injecting apurge gas without interruption while the source gases are being injectedas shown in FIGS. 1A and 2A. Alternatively, purge operation may beperformed by injecting a purge gas between the injection pulses of thesource gases as shown in FIGS. 1B and 2B. The purge gas is Ar, N₂, orHe.

Even when an upper electrode having a complex structure is deposited asin forming a cylinder type capacitor of this embodiment, the stepcoverage of the upper electrode formed according to the presentinvention is very good, thereby allowing fabrication of a capacitorhaving a high dielectric constant and excellent electrical reliability.

Since individual atomic layers are sequentially adsorbed and formed whenforming an upper electrode in the embodiment as described above, thecomposition of the upper electrode can be adjusted more easily and thereproducibility of the composition is excellent compared to CVD. Inother words, the composition of the upper electrode can be easilyadjusted by adjusting only the pulsed injection order of source gasesand the number of pulsed injections of each source gas for the upperelectrode, so that the electrical conductivity and resistance of theupper electrode can be very easily adjusted as necessity requires. Inaddition, reproducibility of the composition is very excellent.

Third Embodiment

With reference to FIGS. 9A through 9E, a trench type capacitor employinga metal layer formed by atomic layer deposition as a lower electrodewill be described. Referring to FIG. 9A, an insulating layer 310composed of a silicon oxide (SiO₂) film is formed on a semiconductorsubstrate 104. Subsequently, photo etching is performed to form acontact hole in the insulating layer 310.

Referring to FIG. 9B, the contact hole may be partially filled to apredetermined depth or not filled at all to give a desired capacitance.When partially filling the contact hole, the contact hole is filled withpolysilicon and then wet etching or wet etching combined with chemicalmechanical polishing is performed on the polysilicon to leave apolysilicon film 312 of a predetermined thickness at the bottom of thecontact hole.

Referring to FIG. 9C, a lower electrode 314 is formed on the insulatinglayer 310 and on the polysilicon film 312. The lower electrode 314 isformed in a similar manner to that used in forming the upper electrode220 in the second embodiment. In other words, the lower electrode 314 isa conductive layer in which a reactive metal (A), an amorphouscombination element (B) for preventing crystallization of the reactivemetal and nitrogen (N), and nitrogen (N) are alternately stacked byatomic layer deposition. The composition ratio of an atomic layer of thelower electrode 314 is determined according to the number of injectionpulses of the atomic layer to the total number of injection pulses usedfor the lower electrode 314, and the electrical conductivity andresistance of the lower electrode 314 can be appropriately determined byadjusting the ratio of the number of atomic layers formed of theamorphous combination element (B) to the combined number of other atomiclayers. The same materials as those used in the second embodiment areused for the reactive metal (A) and the amorphous combination element(B) for preventing crystallization of the reactive metal (A) and thenitrogen (N).

In this embodiment, the lower electrode 314 is formed of a TiAlN layerlike the upper electrode 220 in the second embodiment. When forming theTiAlN layer, one among titanium chloride (TiCl₄), tetrakis demethylamino titanium (TDMAT) and tetrakis deethyl amino titanium (TDEAT) isused as a source gas for Ti when forming a TiAlN layer. One amongtrimethyl aluminum (TMA), triethyl aluminum (TEA), tri-I-buthyl aluminum(TIBA) and AlClx is used as a source gas for Al. One among N₂ and NH₃ isused as a source gas for N.

The following description concerns a method of forming the lowerelectrode 314. The method of forming the lower electrode 314 is similarto the method of forming the upper electrode 220 in the secondembodiment.

To form a TiAlN layer as the lower electrode 314, pulsed injections ofsource gases TiCl₄, TMA and NH₃ of a reactive metal (Ti), an amorphouscombination element (Al) and nitrogen (N), respectively, are supplied,and the source gases are chemically adsorbed to the polysilicon film 312and the insulating layer 310, thereby forming a plurality of atomiclayers.

The lower electrode 314 has a structure in which atomic layerscorresponding to the source gases are alternately stacked since thesource gases are alternately supplied in a predetermined order. Thecomposition ratios of Ti, Al and N constituting the lower electrode 314are determined by appropriately adjusting the number of injections ofeach source gas. By appropriately determining the composition ratios,desirable electrical conductivity and resistance can be accuratelyobtained.

For the adjustment of composition, examples described above withreference to FIGS. 1A through 2B can be adopted, and the same conditionsas described in the examples can be adopted in the deposition of atomiclayers. Purge operation may be performed by continuously injecting apurge gas without interruption while the source gases are being injectedas shown in FIGS. 1A and 2A. Alternatively, purge operation may beperformed by injecting a purge gas between the injection pulses of thesource gases as shown in FIGS. 1B and 2B. The purge gas is Ar, N₂, orHe.

After depositing each atomic layer a predetermined number of times asdescribed above, the lower electrode 314 of a desirable pattern iscompleted using a mask such as a photoresist pattern.

Referring to FIG. 9D, a tantalum oxide film (Ta₂O₅) having a largedielectric constant or a ferroelectric substance, such as PZT ((Pb,Zr)TiO₃), BST ((Ba, Sr)TiO₃) or STO (SrTiO₃), is deposited on the trenchtype lower electrode layer 314 to form a trench type dielectric film318.

Referring to FIG. 9E, an upper electrode 320 is formed on the highdielectric film 318. To prevent oxidation caused by the underlying highdielectric film 318 during a thermal process, the upper electrode 320 isformed such that a metal layer 320 a acting as a barrier layer is formedof TiN or TaN on the high dielectric film 318 and a polysilicon layer320 b is formed on the metal layer 320 a. instead of using the metallayer 320 a and the polysilicon layer 320 b, the upper electrode 320 maybe formed of a metal layer, which is composed of a reactive metal (A),an amorphous combination element (B) for preventing crystallization ofthe reactive metal (A) and nitrogen (N), and nitrogen (N), for example,a TiAlN layer. To achieve excellent step coverage of the trench typehigh dielectric film 318, the upper electrode 320 is preferably formedby atomic layer deposition in the same manner as used in forming thelower electrode 314.

When the lower electrode 314 is formed of a TiAlN layer formed by atomiclayer deposition as described above, the lower electrode 314successfully functions as a barrier metal layer since the TiAlN layerhas excellent thermal and oxidation resistant characteristics.Accordingly, an additional barrier layer does not need to be formedbetween the lower electrode 314 and the underlying polysilicon film 312or the semiconductor substrate 104, which comes in contact with thelower electrode 314, thereby simplifying fabrication.

Since atomic layers are individually deposited in forming the lowerelectrode 314, the step coverage of the lower electrode 314 is excellenteven in a very compact region. Even when a lower electrode having acomplex structure and high aspect ratio is deposited in forming a trenchtype capacitor of this embodiment, the step coverage of the lowerelectrode formed according to the present invention is very good,thereby allowing fabrication of a capacitor having a high dielectricconstant and excellent electrical reliability.

Since individual atomic layers are sequentially adsorbed and formed whenforming a lower electrode in this embodiment as described above, thecomposition of the lower electrode can be adjusted more easily and thereproducibility of the composition is excellent compared to CVD. Inother words, the composition of the lower electrode can be easilyadjusted by adjusting only the pulse injection order of source gases andthe number of injections of each source gas for the lower electrode, sothat the electrical conductivity and resistance of the lower electrodecan be very easily adjusted as necessity requires. In addition,reproducibility of the composition is very excellent.

Method for Forming Metal Layer Using Atomic Layer Deposition Accordingto Second Aspect of the Present Invention

FIG. 10 is a sectional view for explaining a method of forming a metallayer using atomic layer deposition according to a second aspect of thepresent invention.

FIG. 11 is a graph for showing an example of a method of injectingsource and purge gases for deposition of an atomic layer when formingthe oxygen diffusion preventing layer of FIG. 10.

Referring to FIG. 10, a metal layer formed by atomic layer depositionaccording to the second aspect of the present invention is a multiplemetal layer 405. The multiple metal layer 405 is formed by depositing aplurality of metal layers 401 in alternation with a plurality of oxygendiffusion preventing layers 403. The metal layer 401 and the oxygendiffusion preventing layer 403 are formed in situ using atomic layerdeposition equipment. The oxygen diffusion preventing layer 403 isformed thinly, for example, to a thickness of 5-15 Å, not to interferewith the flow of electrons.

The metal layer 401 is formed in the same manner as used in forming ametal layer of the first aspect. In other words, the metal layer 401 isformed in a structure in which a reactive metal (A), an amorphouscombination element (B) for preventing crystallization of the reactivemetal and nitrogen (N), and nitrogen (N) are alternately stacked in anA-B-N structure by atomic layer deposition. More specifically, pulsedinjections of source gases for a reactive metal (A), an amorphouscombination element (B) for preventing crystallization of the reactivemetal (A) and nitrogen (N), and nitrogen (N) are alternately applied toa semiconductor substrate (not shown) in a predetermined order. Thesource gases are sequentially and chemically adsorbed to thesemiconductor substrate, thereby forming an A-B-N structure. The numberof injections of each source gas is adjusted to obtain a desirablecomposition of the metal layer 401.

The reactive metal (A) may be Ti, Ta, W, Zr, Hf, Mo or Nb, and theamorphous combination element (B) may be Ai; Si or B. The metal layer401 is formed under the same conditions (e.g., deposition temperatureand source gases) as those of the method of forming a metal layeraccording to the first aspect of the present invention. The metal layer401 is a TiAlN layer.

Next, the oxygen diffusion preventing layer 403 is formed on the metallayer 401 using atomic layer deposition. The oxygen diffusion preventinglayer 403 prevents permeation of oxygen diffused from the outside. Theoxygen diffusion preventing layer 403 is formed by alternately applyingpulsed injections of a metal element, for example, an aluminum sourcegas, and an oxygen gas to the metal layer 401 as shown in FIG. 11. Inthis aspect, the oxygen diffusion preventing layer 403 is formed of analuminum oxide film. In forming the aluminum oxide film, one amongtrimethyl aluminum (TMA), triethyl aluminum (TEA), tri-I-buthyl aluminum(TIBA) or AlClx is used as an aluminum source gas. One among O₂ and N₂Ois used as an oxygen source gas. One among argon gas, nitrogen gas andhelium gas is used as a purge gas.

The thermal and oxidation resistant characteristics of the multiplemetal layer 405 can be outstandingly improved since the oxygen diffusionpreventing layer 403 is additionally formed on the metal layer 401(between the metal layers 401) which has good thermal and oxidationresistant characteristics as described in the first aspect of thepresent invention. While a metal layer according to the first aspect hasan oxide layer on the surface thereof, the multiple metal layer 405according to the second aspect has the oxygen diffusion preventinglayers 403 therewithin and on the surface thereof, thereby more reliablypreventing diffusion of oxygen.

Method for Forming Metal Layer Using Atomic Layer Deposition Accordingto Third Aspect of the Present Invention

FIGS. 12 and 13 are sectional views for explaining a method of forming ametal layer using atomic layer deposition according to a third aspect ofthe present invention. A metal layer formed by atomic layer depositionaccording to the third aspect of the present invention is a multiplemetal layer 507 as shown in FIG. 13. The multiple metal layer 507 isformed by sequentially depositing a metal layer 501, an oxygen diffusionpreventing layer 503 and a material layer 505 multiple times. The oxygendiffusion preventing layer 503 is spontaneously formed by a thermalprocess as will later be described.

Referring to FIG. 12, the metal layer 501 is formed on a semiconductorsubstrate (not shown). The metal layer 501 is formed in the same manneras used in forming a metal layer of the first aspect of the presentinvention. In other words, the metal layer 501 is formed in a structurein which a reactive metal (A), an amorphous combination element (B) forpreventing crystallization of the reactive metal and nitrogen (N), andnitrogen (N) are sequentially stacked in an A-B-N structure by atomiclayer deposition. The reactive metal (A) may be Ti, Ta, W, Zr, Hf, Mo orNb, and the amorphous combination element (B) may be Al, Si or B as inthe first aspect of the present invention. The metal layer 501 is formedunder the same conditions (e.g., deposition temperature and sourcegases) as those of the method of forming a metal layer according to thefirst or second aspect of the present invention. The metal layer 501 isa TiAlN layer.

Next, the material layer 505 containing oxygen is formed on the metallayer 501 using atomic layer deposition. In this aspect of the presentinvention, the material layer 505 is formed of a TiON film. In otherwords, pulsed injections of titanium, oxygen and nitrogen source gasesare alternately supplied to an atomic layer deposition chamber in apredetermined order, thereby forming the TiON film.

Referring to FIG. 13, a thermal process is performed on thesemiconductor substrate including the metal layer 501 and the materiallayer 505 to thereby form the oxygen diffusion preventing layer 503between the metal layer 501 and the material layer 505. The metalsubstance of the metal layer 501 reacts with the oxygen of the materiallayer 505, thereby forming the oxygen diffusion preventing layer 503.For example, when the metal layer 501 is formed of a TiAlN film and thematerial layer 505 is formed of a TiON film, the aluminum in the metallayer 501 drifts to the surface of the metal layer 501 and reacts withthe oxygen contained in the material layer 505, thereby forming theoxygen diffusion preventing layer 503 of an aluminum oxide film. Themultiple metal layer 507 according to the third aspect includes aplurality of structures, each of which is composed of the metal layer501, the oxygen diffusion preventing layer 503 and the material layer505 which are sequentially stacked.

The thermal and oxidation resistant characteristics of the multiplemetal layer 507 can be outstandingly improved since the oxygen diffusionpreventing layer 503 is additionally formed on the metal layer 501(between the metal layers 501) having good thermal and oxidationresistant characteristics as described in the first aspect of thepresent invention.

With reference to FIGS. 14 and 15, a method for fabricating asemiconductor device employing a metal layer, which is formed by atomiclayer deposition according to the second and third aspects of thepresent invention, as a barrier metal layer will be described in detail.Referring to FIG. 14, an insulating layer 603 composed of a siliconoxide (SiO₂) film is formed on a semiconductor substrate 601.Subsequently, photo etching is performed to form a contact hole in theinsulating layer 603. Next, the contact hole is filled with apolysilicon film to a predetermined height to form a plug 605 which is aconductive material film. The plug 605 is formed by depositingpolysilicon over the insulating layer 603 and in the contact hole andthen performing wet etching or wet etching combined with chemicalmechanical polishing on the polysilicon to leave the polysilicon of apredetermined thickness at the bottom of the contact hole.

Referring to FIG. 15, a metal layer is formed on the entire surface ofthe semiconductor substrate 601 including the plug 605. An etchback orchemical mechanical polishing process is performed on the metal layer toform a barrier metal layer 607 filling the contact hole. The barriermetal layer 607 is formed in the same manner as used in forming a metallayer according to the second or third aspect of the present invention.In other words, the barrier metal layer 607 may be a multiple metallayer which is formed by repeatedly, e.g., 3-10 times, stacking atwo-layer structure in which a metal layer having a reactive metal(A)-amorphous combination element (B)-nitrogen (N) structure formed byatomic layer deposition and an oxygen diffusion preventing layer havinga thickness of 5-15 A are sequentially stacked. Alternately, the barriermetal layer 607 may be a multiple metal layer which is formed byrepeatedly, e.g., 3-10 times, stacking a three-layer structure in whicha metal layer having an A-B-N structure, an oxygen diffusion preventionlayer and a material layer are sequentially stacked.

The reactive metal (A) may be Ti, Ta, W, Zr, Hf, Mo or Nb, and theamorphous combination element (B) may be Al, Si or B. In thisembodiment, the barrier metal layer 607 is formed of a TiAlN layer to athickness of 50-500 Å. When the barrier metal layer 607 is formed of amultiple metal layer, oxidation of the plug 605 can be more reliablyprevented during a thermal process.

Next, a lower electrode 609 is formed on the semiconductor substrate 601including the barrier metal layer 607. The lower electrode 609 is formedof platinum (Pt), ruthenium (Ru), iridium (Ir), ruthenium oxide (RuO₂)or iridium oxide (IrO₂). A tantalum oxide film (Ta₂O₅) or aferroelectric substance, such as PZT ((Pb, Zr)TiO₃), BST ((Ba, Sr)TiO₃)or STO (SrTiO₃) having a large dielectric constant, is deposited on thelower electrode layer 609 to form a dielectric film 611. Then, an upperelectrode 613 is formed on the dielectric film 611. The upper electrode613 is formed of the same substance as the lower electrode 609.

As described above, a metal layer or a multiple metal layer formed byatomic layer deposition of the present invention has a high thermal andoxidation resistant characteristics. Since a metal layer of a multiplemetal layer of the present invention is formed by individuallydepositing atomic layers, the step coverage thereof is excellent even ina very compact region. In addition, since individual atomic layers areadsorbed and formed in a predetermined order in atomic layer depositionof the present invention, the composition ratio of each elementcontained in the metal layer or the multiple metal layer can be easilyadjusted, and the reproducibility of the composition is excellent ascompared with CVD.

According to atomic layer deposition of the present invention, thecomposition ratio of each element of a metal layer or a multiple metallayer can be desirably adjusted only by appropriately determining thenumber of pulsed injections of a source gas. Accordingly, the resistanceand electrical conductivity of the metal layer or the multiple metallayer can be very conveniently adjusted.

A metal layer or a multiple metal layer formed by atomic layerdeposition of the present invention may be used as a barrier metallayer, a lower electrode or an upper electrode in a semiconductordevice. When a metal layer or a multiple metal layer of the presentinvention is used as a barrier metal layer, oxidation of a polysiliconplug can be prevented in addition to the effects described above. When ametal layer or a multiple metal layer of the present invention is usedas a lower electrode, an additional barrier metal layer does not need tobe formed between the lower electrode and a substrate, therebysimplifying the fabrication. When a metal layer or a multiple metallayer of the present invention is used as an upper electrode, thecomposition of the upper electrode can be easily adjusted, therebyfacilitating adjustment of the electrical conductivity and resistance.

What is claimed is:
 1. A semiconductor device comprising: an insulatingfilm including a contact hole in a semiconductor substrate; a conductivematerial film in the contact hole on the semiconductor substrate; acapacitor comprising a lower electrode on the conductive material filmin the contact hole, a high dielectric film on the lower electrode andan upper electrode on the high dielectric film; and a barrier metallayer between the conductive material film in the contact hole and thelower electrode, the barrier metal layer comprising an A-B-N structureof a layer of reactive metal (A) that is on a layer of an amorphouscombination element (B) for preventing crystallization of the reactivemetal (A) and nitrogen (N), and that is on a layer of nitrogen (N). 2.The semiconductor device of claim 1, wherein the reactive metal (A) isone selected from the group consisting of titanium (Ti), tantalum (Ta),tungsten (W), zirconium (Zr), hafnium (Hf), molybdenum (Mo) and niobium(Nb).
 3. The semiconductor device of claim 1, wherein the amorphouscombination element (B) for preventing crystallization of the reactivemetal (A) and the nitrogen (N) is one selected from the group consistingof aluminum (Al), silicon (Si) and boron (B).
 4. The semiconductordevice of claim 1, wherein the electrical conductivity and resistance ofthe barrier metal layer is determined by the number of injection pulsesof an atomic layer of an amorphous combination element to the totalnumber of injection pulses used for the barrier metal layer.
 5. Thesemiconductor device of claim 1, wherein the specific resistance of thebarrier metal layer increases as the content of Al increases relative tothe content of Ti in the barrier metal layer.
 6. The semiconductordevice of claim 1, wherein the content of Al with respect to thereactive metal is 10-35% when the barrier metal layer is formed ofTiAlN.
 7. The semiconductor device of claim 1, further comprising anoxygen diffusion preventing layer on the metal layer, wherein thebarrier metal layer may be formed of a multiple metal layer comprising aplurality of metal layers and a plurality of oxygen diffusion preventinglayers.
 8. The semiconductor device of claim 7, further comprising amaterial layer containing oxygen on the oxygen diffusion preventinglayer.
 9. A semiconductor device having a capacitor comprising a lowerelectrode on a predetermined material film on a semiconductor substrate,a high dielectric film on the lower electrode and an upper electrode onthe high dielectric film, wherein the lower electrode is an A-B-Nstructure of a layer of reactive metal (A) that is on a layer of anamorphous combination element (B) for preventing crystallization of thereactive metal (A) and nitrogen (N), and that is on a layer ofnitrogen(N).
 10. The semiconductor device of claim 9, wherein thereactive metal (A) is one selected from the group consisting of titanium(Ti), tantalum (Ta), tungsten (W), zirconium (Zr), hafnium (Hf),molybdenum (Mo) and niobium (Nb).
 11. The semiconductor device of claim9, wherein the amorphous combination element (B) for preventingcrystallization of the reactive metal (A) and the nitrogen (N) issilicon (Si) or boron (B).
 12. The semiconductor device of claim 9,wherein the amorphous combination element (B) for preventingcrystallization of the reactive metal (A) and the nitrogen (N) isaluminum (Al).
 13. The semiconductor device of claim 9, wherein theelectrical conductivity and resistance of the lower electrode isdetermined by the ratio of the number of depositions of an atomic layerof the amorphous combination element to the total number of depositionsused for the lower electrode.